Isuzu 4HK1 / 6HK1 — Valve clearance inspection and adjustment
Adjustments · Valve train
For the Isuzu 4HK1 / 6HK1, from the Isuzu service manual.
Applies to: Isuzu 4HK1, Isuzu 6HK1
Before you start
- Adjust while cold.
- Ensure bridge is level and hits both valve axis ends.
- Avoid seizing bridge guide.
Procedure
- Remove cylinder head cover and fuel injector harness ASM.
- Remove leak off pipe and rotate crankshaft to No.1 cylinder compression TDC.
- Insert 0.4 mm thickness gauge between rocker arm and bridge to check clearance.
- Loosen all bridge and rocker arm adjusting nuts and screws (4HK1: 8 nuts/8 screws; 6HK1: 12 nuts/12 screws).
- Place 0.4 mm thickness gauge between No.1 cylinder rocker arm end and bridge cap.
- Tighten rocker arm adjusting screw until gauge is snug, then tighten lock nut.
- Tighten bridge adjusting screw until bridge contacts valve head, then tighten lock nut.
- Check gauge snugness; adjust if too tight.
- Remove gauge and repeat for remaining cylinders.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve clearance: 0.4 mm cold (intake and exhaust)
- Valve bridge clearance: 0.1 mm or less
- Tightening torque: 22 N·m (16 lb ft) for rocker arm and bridge adjustment screw nuts
Full service-parts list: Isuzu 4HK1 →, Isuzu 6HK1 →
Source: Isuzu service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.